PRUNING— THE AMOUNT OR SEVERITY 



413 



Table 8. — Effect of Pruning on Leaf Surface and Top and Root Growth of 



Peach Trees 4 Years Old at Beginning of Experiment 



(After Chandler^') 



the weight of the prunings has been added to that of tlie tree, the t(jtal weight 

 of pruned and unpruned trees is practically the same. The root growth, how- 

 ever, has been greatly reduced. When it is considered that this reduction in 

 growth has occurred during the last 2 years of the 6 years during which the trees 

 have been in the orchard, it will be realized how striking the reduction is. Thus 

 if at the beginning of 1916 the roots weighed 15 pounds, then the root growth 

 on the unpruned trees since that time has been nearly twice that on the pruned 

 tree. Unfortunately we have no records as to the root weight of trees 4 years 

 old, but it must have been 10 pounds or more, since by records that we have the 

 tops would then have weighed from 30 to 35 pounds. If the root weight at the 

 beginning was 10 pounds, then the root growth in the pruned trees since that 

 time has been but 65 per cent, of that made by the unpruned trees." 



In effect the influence of a heavy top pruning on the subsequent 

 development of the tree is more or less comparable to that of a root 

 pruning. 



Presumably, pruning practices which do not reduce top growth in 

 trees of other kinds or of greater age than those studied would not have 

 such an influence on root growth; exact data, however, are lacking. It 

 is significant, nevertheless, that in young trees pruning of the top has 

 been found greatly to influence the extent of root development the 

 following season. This suggests one of the indirect ways through which 

 pruning one season may influence growth and development 2 or 3 years 

 later. 



Influence on Fruit Spur and Fruit-bud Formation. — In Table 6 

 are presented data on the influence of varying amounts of pruning on 

 fruit spur formation in young apple trees. The less the pruning the larger 

 is the number of fruit spurs formed. With very severe pruning there is a 



